78 280 has been sitting . . .

[Biker_Trash]

New to the forum, so hello! Had a few Zs back 20 years ago as a kid. I recently picked up a pair of 78s both of which have been sitting awhile.

The one I'm working on now has been off the road since 2003. The previous owner had it a couple of years and it sat unused. Prior to that, it was stored by the original owner's son where it also sat, being started occassionally. The Z has rust and is nothing special, but hasn't been hacked on so I picked it up. The owner I bought it from said he started it once a month, but it had recently quit starting. While I was there, he started it on a bottle at the air flow sensor (yikes!) but I heard the car run and it sounded good. So, I figured the fuel pump.

I picked up a used fuel pump and replaced the one on the car which was gunked up. I drained the gas tank of approximately 5 gallons of old fuel and replaced it with 10 gallons of fresh stuff. New oil and filter, new gas filter, new air filter, new battery. Went to start it and it just cranks. Checked for spark and I've got it at the plugs.

So, I'm figuring it is still a fuel supply issue. When I turn the key on, I don't hear anything until the car cranks over. Is that a problem? Once I let off the key, I hear a buzz which the wife tells me is coming from "back there" (I'm in the car and hear it but can't tell from where). I pulled the fuel line where it enters the rail and had plenty of pressure (poof!!). I ran the fuel line into a container and cranked the engine over about three times for maybe 7 or 8 seconds each time. I checked the container and there was maybe a tablespoon or two of gas in it. Does that sound about right or should there have been more?

I'm not a mechanic by trade (big surprise reading this!) but I'm not completely helpless, either. Old motorcycles are more my thing.

So, if I don't hear the fuel pump when I turn on the ignition, is that a bad pump? If the fuel rail pressurizes and I get a little gas, does that indicate the fuel pump is working? What do I need to be checking next? Remember, the car ran off a bottle and I have spark at the plug. All help appreciated!

Jeff Woodard

[WingZr0]

Yeap, sounds like your pumps shot mate, might as well do the Fuel Damper too which is next the pump. You most likely need to clean out your tank and fuel lines and rails, specially if the old gas was gooey. That sound likely the fuel pump struggling. You read The Horse or Back Street Choppers by chance

Edited January 12, 2010 by WingZr0

[IdahoKidd]

Sounds like it is working correctly. The fuel pump will come on for 5 seconds or so when you first turn the switch on and then stop. On your 78, you will see two wires on the oil pressure switch down near the oil filter. One of these interupts the fuel pump signal with loss of oil pressure (in case the motor dies in an accident or such the fuel pump doesn't keep pumping).

Down on the starter motor is a light gauge wire with a spade clip on it. Unhook this off the starter. This keeps the engine from turning over but fools the pump into pumping during the crank cycle. Unhook the fuel line between the fuel filter and the engine and run a line from the filter into a container. Turn the key to the crank cycle and hold it on. Fuel should readily come out as long as the key is held in start position. It should be a considerable amount of fuel. If there isn't, then do the same before the fuel filter. If still no fuel, then you have a blockage somewhere. If you do get fuel (key back to off), hook the line back up to the engine and unhook the return line next to the filter and capture it into a container. Turn the key to crank and let it push the old gas out of that part of the system as well. Hook the lines back up and remember to hook the wire back to the starter. These cars can accumulate a lot of "crud" in the tank and you might plan on cleaning out the tank and be prepared to change out a filter or two until it gets stable again. Good luck!

[Biker_Trash]

WingZr0 - yes, The Horse is the only mag I pay for.

IdahoKidd said, "Sounds like it is working correctly. The fuel pump will come on for 5 seconds or so when you first turn the switch on and then stop." Mine doesn't do that. I don't get any noise until AFTER I'm done cranking, and I'm not sure where that sound is coming from. So maybe my pump isn't working correctly?

How do you clean your fuel lines? Compressed air? I'm really wondering about the line from the pump to the filter. If I'm only getting a couple of tablespoons of gas but should be getting "a considerable amount", then maybe it's the fuel line?

Jeff

[WingZr0]

Double post see below. . . .

Edited January 12, 2010 by WingZr0

[WingZr0]

HAHA you sound like me with my Dsport subscription. Truely great mag that Horse. Try that trick Idaho says as its new to me so if your pump does work then your lines are clogged instead. What was the condition of old gas. A 78 Z i sold sat for about 5 years and the gas in it smelled like varnish, had clumps of VERY STICKY gooey stuff, cranked but would not start. un hooked the line before the fuel filter, cranked it again few times and still no gas. Tuned out to be clogged pump. Compressed air is one way to do it.

Edited January 14, 2010 by WingZr0

[Biker_Trash]

EUREKA! SHE LIVES!!!

I pulled the fuel pump and checked it on the battery and it was working. I blew out the lines and the fuel rail . . . fuel rail resisted at first which I figure was my problem. Took a little cranking but she's running!! Now I have two more questions . . .

First, and most worrisome, is I didn't have a lot of oil pressure (new oil + filter already). I did have pressure and at a bit higher revs, it was maybe 30 on the 90 scale, but most of the time it hovered around 10 or so. Is this telling me bad news or is it just a factor of having sat so long and as things circulate it will get better? I didn't run it long at all because the pressure worried me.

Second, my gas pedal depresses but doesn't 'release' and come back up . . . stays at the point I push it. Is there a spring I need to look for or vaccuum tube or ??

Thanks in advance!!

Jeff Woodard

[WingZr0]

Glad you got juice ! For the gas pedal try using the throttle linkage with your hand in the engine bay with your hands and see if it's sticking or if the pedal is . If so STP the entire thing, all connections and retainers, return springs on the throttl and the pedal parts under the dash. Your oil stop may just be bad unless the oil pressure sender is bad or the dash gauge. Replaced my oil pump and the guage still says 0 to 10 if lucky. Don't know how you would test for which but it might be good to replace the old pump anyway IMO and see wat happens.

Edited January 14, 2010 by WingZr0